EP3510072B1 - Polyamide foams which do not extend fire for filling cavities in mining - Google Patents

Description

The present invention relates to a method for producing non-fire-propagating polyamide foams and a method for filling cavities in mining, tunneling, civil engineering or in oil and gas production.

For safety reasons in civil engineering and mining, e.g. B. tunnel construction, tunnel construction or mining, occurring cavities are filled in order to prevent detachment of rock or collapses. As a rule, this is done with the help of self-foaming, curable compositions. The hardenable form is created by mixing two components, which are then introduced into the cavity, where they form a foam under the ambient conditions and harden in a chemical reaction. An example of this is polyurethanes or polyurea silicates.

In coal mining, however, only cavity fillers that do not pass on a fire may be used. The fire propagation behavior can be determined by the so-called punking test (BS 5946: 1980). In this test, a piece of foam is locally heated with a Bunsen burner and it is checked whether the fire front progresses after the flame has been removed. Many of the classic cavity fillers do not meet this requirement. Well-known examples of non-fire propagating cavity fillers are phenol-formaldehyde resin based foams. However, the phenol content of preparations is subject to legal regulations. For reasons of occupational hygiene, it is therefore desirable to have phenol-free alternatives.

From the DE 2 150 151 A1 foams made from aromatic polyamides are known which are non-flammable or self-extinguishing. They are produced by reacting an aromatic diisocyanate with at least one difunctional aromatic compound with an acid function in bulk in the molten state. In order to melt the aromatic dicarboxylic acids, however, temperatures of 180 to 320 ° C are required. This makes it impossible to use the foams described in mining; here a method is desirable in which two components which are liquid at ambient temperatures are mixed to produce the foam. Attempts to dissolve or disperse the solid aromatic dicarboxylic acids in thinners or solvents and to use them in this form have led to a deterioration in the mechanical properties of the foams.

The WO 2016/127016 discloses compositions for forming heat-resistant foams which comprise an organic polyisocyanate, a polycarboxylic acid, a polyol, a surfactant and a catalyst. Suitable polycarboxylic acids include dimer and trimer fatty acids.

The WO 93/15121 describes a process for the production of thermoplastic or thermosetting plastics with amide groups by catalytic reaction of polyvalent isocyanates with carboxylic acids and optionally alcohols or polyvalent amines to form CO ₂ .

The present invention is based on the object of specifying a process for the production of non-fire-propagating, aromatic polyamide foams which uses two components which are liquid at ambient temperatures and which provides foams of suitable mechanical strength.

1. (i) einer flüssigen Isocyanatkomponente, die wenigstens ein Polyisocyanat enthält und worin das Molverhältnis von aromatischen Isocyanat-Gruppen zur Summe von aromatischen und aliphatischen Isocyanat-Gruppen wenigstens 60 Mol-% beträgt, mit
2. (ii) wenigstens einer flüssigen Isocyanat-reaktiven Komponente, welche einen Reaktivverdünner enthält und der Reaktivverdünner umfasst
   1. (a) einen kettenverlängernden und/oder vernetzenden Reaktivverdünner, der ausgewählt ist unter aliphatischen verzweigten C_24-66-Polycarbonsäuren, alicyclischen C_24-66-Polycarbonsäuren und Partialestern von Polycarbonsäuren mit wenigstens zwei unveresterten Carboxylgruppen und/oder
   2. (b) einen kettenabschließenden Reaktivverdünner, der ausgewählt ist unter aliphatischen verzweigten C_24-66-Monocarbonsäuren, alicyclischen C_24-66-Monocarbonsäuren und Partialestern von Polycarbonsäuren mit einer unveresterten Carboxylgruppe, und
3. (iii) gegebenenfalls einer festen Isocyanat-reaktiven Komponente,

wobei die flüssige Isocyanat-reaktive Komponente und/oder die feste Isocyanat-reaktive Komponente eine aromatische C_8-18-Polycarbonsäure und/oder ein Anhydrid davon umfasst.The object is achieved by a process for producing non-fire-propagating polyamide foams by mixing

1. (i) a liquid isocyanate component which contains at least one polyisocyanate and in which the molar ratio of aromatic isocyanate groups to the sum of aromatic and aliphatic isocyanate groups is at least 60 mol%, with
2. (ii) at least one liquid isocyanate-reactive component which contains a reactive diluent and which comprises reactive diluent
   1. (a) a chain-extending and / or crosslinking reactive diluent, which is selected from aliphatic branched C _24-66 polycarboxylic acids, alicyclic C _24-66 polycarboxylic acids and _partial esters of polycarboxylic acids with at least two unesterified carboxyl groups and / or
   2. (b) a chain terminating reactive diluent which is selected from aliphatic branched C _{24-66 monocarboxylic} acids, alicyclic C _24-66 monocarboxylic acids and _partial esters of polycarboxylic acids with an unesterified carboxyl group, and
3. (iii) optionally a solid isocyanate-reactive component,

wherein the liquid isocyanate-reactive component and / or the solid isocyanate-reactive component comprises an aromatic C _8-18 polycarboxylic acid and / or an anhydride thereof.

A polycarboxylic acid is understood here to mean a carboxylic acid which has at least two carboxyl groups, e.g. B. a dicarboxylic acid,

Tricarboxylic acid and / or tetracarboxylic acid. In the present case, a liquid component is understood to mean a substance or mixture of substances which is in liquid, pumpable form at ambient conditions (25 ° C., 1 bar). This includes e.g. B. solutions or suspensions, preferably solutions.

Carboxyl groups develop carbon dioxide when reacted with isocyanates; The resulting carbon dioxide acts as a foaming agent. An amide bond is formed from the carboxyl group and the isocyanate group. According to the invention, certain reactive diluents are also used which allow simplified handling of the otherwise solid polycarboxylic acids and implementation under comparatively mild conditions. The reactive diluents take part in the polyaddition reaction; they therefore do not evaporate from the finished foam and do not significantly impair its mechanical properties.

In the present process for producing non-fire-propagating polyamide foams, a liquid isocyanate component which contains a polyisocyanate and a liquid isocyanate-reactive component which contains a reactive diluent are mixed together. Optionally, an additional solid isocyanate-reactive component can be added or predispersed in the liquid isocyanate-reactive component. The reactive diluent used according to the invention can have a chain-extending and / or cross-linking effect if it has at least two carboxyl groups, or a chain-terminator if it has a carboxyl group. The liquid and / or solid isocyanate-reactive component comprise / comprises at least one aromatic C _8-18 polycarboxylic acid and / or an anhydride thereof.

The components are preferably mixed in amounts such that 0.2 to 2 equivalents of carboxylic acid groups, calculated as the sum of the carboxylic acid and / or anhydride groups in the liquid isocyanate-reactive component and the solid isocyanate-reactive component, to one equivalent of the NCO groups Isocyanate components are eliminated.

Mixing is suitably carried out at a temperature of 0 to 80 ° C, especially 10 to 60 ° C. As a rule, the components do not have to be preheated or tempered only slightly, which greatly facilitates the practice of the method according to the invention. Foaming starts spontaneously and the initially liquid viscous foam hardens itself. The reaction is slightly exothermic. Mixing can be done by mixing with a stirrer. Preferably, however, the components are pumped separately to a mixing unit and z. B. homogenized in a static mixer.

The liquid isocyanate component contains aromatic polyisocyanates and may include aliphatic polyisocyanates, including cycloaliphatic polyisocyanates, provided that the molar ratio of aromatic isocyanate groups to the sum of aromatic and aliphatic isocyanate groups is at least 60 mol%, preferably at least 80 mol% , in particular at least 90 mol% and particularly preferably at least 95 mol%. In certain embodiments, the liquid isocyanate component essentially contains only polyisocyanates with only aromatic isocyanate groups. Aromatic isocyanate groups are those isocyanate groups which are bonded directly to an aromatic ring. Aliphatic isocyanate groups are those isocyanate groups which are attached to a non-aromatic carbon atom. Therefore, for example, the isocyanate groups in m-xylylene diisocyanate - although the molecule comprises an aromatic benzene ring - are to be regarded as aliphatic isocyanate groups since they are only indirectly bonded to the benzene ring via methylene groups. It is assumed that the molar ratio of aromatic isocyanate groups to the sum of aromatic and aliphatic isocyanate groups in the specified range is responsible for the non-fire-propagating property of the foams obtained.

The isocyanate component preferably has an NCO functionality of at least 1.8, preferably 1.8 to 5 and more preferably 2.1 to 4. The polyisocyanates which can be used preferably have a content of isocyanate groups (calculated as NCO, molecular weight = 42) of 10 to 60% by weight, based on the polyisocyanate (mixture), preferably 15 to 60% by weight and particularly preferably 20 to 55% by weight. -%.

Examples of aromatic polyisocyanates are 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate (MDI) and their isomer mixtures, mixtures of monomeric diphenylmethane diisocyanates and higher core homologues of diphenylmethane diisocyanate (polymer MDI), 2,4- or 2 , 6-tolylene diisocyanate (TDI) and their isomer mixtures, 1,3- or 1,4-phenylene diisocyanate, 1-chloro-2,4-phenylene diisocyanate, 1,5-naphthylene diisocyanate (NDI), diphenylene 4,4'- diisocyanate, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 3-methyl-diphenylmethane-4,4'-diisocyanate, tetramethylxylylene diisocyanate, 1,4-diisocyanatobenzene or diphenyl ether-4,4'-diisocyanate.

Aliphatic diisocyanates that can be used to a limited extent are tetramethylene diisocyanate, hexamethylene diisocyanate (1,6-diisocyanatohexane), octamethylene diisocyanate, decamethylene diisocyanate, Dodecamethylene diisocyanate, tetradecamethylene diisocyanate, derivatives of lysine diisocyanate, m- or p-xylylene diisocyanate, tetramethylxylylene diisocyanate, trimethylhexane diisocyanate or tetramethylhexane diisocyanate, cycloaliphatic diisocyanates such as 1,4-, 1,3- or 1,2-diisocyanate such as 1,4-, 4,4- or 1,2-diisocyanate -Di (isocyanatocyclohexyl) methane, 1-isocyanato-3,3,5-trimethyl-5- (isocyanatomethyl) cyclohexane (isophorone diisocyanate), 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane or 2,4-, or 2,6-diisocyanato-1-methylcyclohexane and 3 (or 4), 8 (or 9) bis (isocyanato-methyl) -tricyclo [5.2.1.0 ²⁶ ] decane isomer mixtures.

Also suitable as polyisocyanates are polyisocyanates containing isocyanurate groups, uretdione diisocyanates, polyisocyanates containing biuret groups, polyisocyanates containing urethane or allophanate groups, polyisocyanates containing oxadiazinetrione groups, uretonimine-modified polyisocyanates of straight-chain or branched C ₄ -C ₂₀ -alkylene diisocyanate diisocyanates, cyclo.

1. 1. Isocyanuratgruppen aufweisende Polyisocyanate von aromatischen, aliphatischen und/oder cycloaliphatischen Diisocyanaten. Bei den dabei vorliegenden Isocyanuraten handelt es sich insbesondere um cyclische Trimere der Diisocyanate, oder um Gemische mit ihren höheren, mehr als einen Isocyanuratring aufweisenden Homologen.
2. 2. Uretdiondiisocyanate mit aromatisch, aliphatisch und/oder cycloaliphatisch gebundenen Isocyanatgruppen. Bei Uretdiondiisocyanaten handelt es sich um cyclische Dimerisierungsprodukte von Diisocyanaten.
3. 3. Biuretgruppen aufweisende Polyisocyanate mit aromatisch, aliphatisch oder cycloaliphatisch gebundenen Isocyanatgruppen.
4. 4. Urethan- und/oder Allophanatgruppen aufweisende Polyisocyanate mit aromatisch, aliphatisch oder cycloaliphatisch gebundenen Isocyanatgruppen, wie sie beispielsweise durch Umsetzung von überschüssigen Mengen an Diisocyanat mit mehrwertigen Alkoholen wie z.B. Trimethylolpropan, Neopentylglykol, Pentaerythrit, 1,4-Butandiol, 1,6-Hexandiol, 1,3-Propandiol, Ethylenglykol, Diethylenglykol, Glycerin, 1,2-Dihydroxypropan oder deren Gemische erhalten werden können.
5. 5. Oxadiazintriongruppen enthaltende Polyisocyanate.
6. 6. Uretonimin-modifizierte Polyisocyanate.

Are also suitable

1. 1. Isocyanurate group-containing polyisocyanates of aromatic, aliphatic and / or cycloaliphatic diisocyanates. The isocyanurates present here are, in particular, cyclic trimers of the diisocyanates, or mixtures with their higher homologues which have more than one isocyanurate ring.
2. 2. Uretdione diisocyanates with aromatic, aliphatic and / or cycloaliphatic isocyanate groups. Uretdione diisocyanates are cyclic dimerization products of diisocyanates.
3. 3. Biuret groups containing polyisocyanates with aromatic, aliphatic or cycloaliphatic isocyanate groups.
4. 4. Polyisocyanates containing urethane and / or allophanate groups with aromatically, aliphatically or cycloaliphatically bound isocyanate groups, such as, for example, by reacting excess amounts of diisocyanate with polyhydric alcohols such as trimethylolpropane, neopentylglycol, pentaerythritol, 1,4-butanediol, 1,6- Hexanediol, 1,3-propanediol, ethylene glycol, diethylene glycol, glycerin, 1,2-dihydroxypropane or mixtures thereof can be obtained.
5. 5. Polyisocyanates containing oxadiazinetrione groups.
6. 6. Uretonimine-modified polyisocyanates.

Polyisocyanates can also be used in the form of polyisocyanate prepolymers. These polyisocyanate prepolymers can be obtained by using the polyisocyanates described above in excess, for example at temperatures of 30 to 100 ° C, preferably at about 80 ° C, with polyols to form the prepolymer.

Monomeric diphenylmethane diisocyanate, for example 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate or isomer mixtures thereof, are preferably used as polyisocyanates. The diphenylmethane diisocyanate can also be used as a mixture with its derivatives. Diphenylmethane diisocyanate can particularly preferably contain up to 10% by weight, further particularly preferably up to 5% by weight, of carbodiimide, uretdione, allophanate or uretonimine-modified diphenylmethane diisocyanate, in particular carbodiimide-modified diphenylmethane diisocyanate.

The liquid isocyanate-reactive component contains a reactive diluent. The reactive diluent is selected from (a) chain-extending and / or cross-linking reactive diluent and (b) chain-terminating reactive diluent or mixtures thereof. Embodiments are preferred which use at least one chain-extending and / or cross-linking reactive diluent. Chain- _extending and / or cross-linking reactive diluents include aliphatic branched C _{24-66 polycarboxylic} acids, alicyclic C _24-66 polycarboxylic acids and _partial esters of polycarboxylic acids with at least two unesterified carboxyl groups. Branched C _{24-66 polycarboxylic} acids preferably have at least one branch _originating from the longest linear carbon chain and comprising at least four carbon atoms. The branched C _{24-66 polycarboxylic} acids and / or alicyclic C _{24-66 polycarboxylic} acids are preferably selected from dimeric fatty acids, trimeric fatty acids and mixtures thereof, which are optionally hydrogenated.

The oligomerization of unsaturated fatty acids is a well-known electrocyclic reaction, which is reviewed, for example, by A. Behr in Fat Sei. Technol. 93, 340 (1991 ), G. Spiteller in Fat Sei. Technol. 94, 41 (1992 ) or P. Daute et al. in Fat Sei. Technol. 95, 91 (1993 ) is reported. In oligomerization, an average of two to three fatty acids come together and form dimers or trimers, which predominantly have branched and / or cycloaliphatic structures. In addition to the fraction of the dimers and trimers, a so-called monomer fraction is obtained, which contains unreacted starting materials and branched monomers which have arisen in the course of the reaction by isomerization. In addition, there is of course a fraction of higher oligomers, which, however, is usually not of major importance. The oligomerization can be carried out thermally or in the presence of noble metal catalysts. The reaction is preferably carried out in the presence of clays such as, for example, montmorillonite, cf. Fats, soaps, Paint 72, 667 (1970 ). The regulation of the content of dimers and trimers and the extent of the monomer fraction can be controlled by the reaction conditions. Technical mixtures can finally also be purified by distillation.

Technical unsaturated fatty acids with 12 to 22, preferably 16 to 18 carbon atoms are suitable as starting materials for the oligomerization. Typical examples are palmoleic acid, oleic acid, elaidic acid, petroselinyl acid, linoleic acid, linolenic acid, conjuene fatty acid, elaeostearic acid, ricinoleic acid, gadoleic acid, erucic acid and their technical mixtures with saturated fatty acids. Typical examples of suitable technical mixtures are uncured split fatty acids of natural triglycerides with iodine numbers in the range from 40 to 140, such as palm fatty acid, tallow fatty acid, rapeseed oil fatty acid, sunflower fatty acid and the like. Split fatty acids with a high oleic acid content are preferred. In addition to the fatty acids, their esters, preferably methyl esters, can also be dimerized. It is also possible to oligomerize the acid and convert it to the methyl ester before the hydrogenation. The ester group can be converted into the acid group in a manner known per se.

Dimer fatty acids, which are particularly preferred for the purposes of the invention, are obtained by oligomerizing technical oleic acid and preferably have a dimer content of 50 to 99% by weight and a trimer content of 1 to 50% by weight. The content of monomers can be 0 to 15% by weight and, if necessary, reduced by distillation. The% by weight are based on the total amount of fatty acid oligomer.

worin a + b = 12 und x +y = 14

worin c + d = 19 und m + n = 14.Suitable fatty acid dimers have the formula HOOC-Dim-COOH, in which Dim represents one of the following radicals:

where a + b = 12 and x + y = 14

where c + d = 19 and m + n = 14.

Alternatively or additionally, partial esters of polycarboxylic acids can be used as reactive diluents. Suitable chain extenders and / or crosslinking reactive thinners are, for. B. monoesters of trimellitic acid, mono- or diesters of tetracarboxybenzene etc. Suitable alcohol components of the partial esters include n-butanol, iso-butanol, n-hexanol, n-heptanol, 2-ethylhexanol, n-octanol, iso-nonanol, cis-9 -Octadecenol, benzyl alcohol etc.

Chain terminating reactive diluents include C _24-66 aliphatic branched _{monocarboxylic} acids and C _24-66 alicyclic _{monocarboxylic} acids. Aliphatic branched monocarboxylic acids can be prepared by oxidation of oxo aldehydes, which in turn can be obtained by hydroformylation of olefin oligomers.

Further chain-closing reactive diluents include partial esters of polycarboxylic acids with an unesterified carboxyl functionality. Suitable acid components of the partial esters include phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, tetracarboxybenzene, naphthalenedicarboxylic acid, adipic acid, sebacic acid, cyclohexanedicarboxylic acid etc. Preferably, partial esters of aromatic polycarboxylic acids are used. As chain-closing reactive diluents, phthalic acid monoesters, terephthalic acid monoesters, diesters of trimellitic acid, triesters of tetracarboxybenzene, naphthalenedicarboxylic acid monoesters, adipic acid monoesters, Sebacic acid monoesters, cyclohexanedicarboxylic acid monoesters etc. can be used. Suitable alcohol components of the partial esters include n-butanol, iso-butanol, n-hexanol,
n-heptanol, 2-ethylhexanol, n-octanol, iso-nonanol, cis-9-octadecenol, benzyl alcohol etc.

The liquid isocyanate-reactive component and / or the solid isocyanate-reactive component comprise an aromatic C _8-18 polycarboxylic acid and / or an anhydride thereof. The aromatic C _8-18 polycarboxylic acid serves as a crosslinker and as a carbon dioxide generator. The use of an aromatic polycarboxylic acid contributes to the non-fire-propagating property of the foams obtained. To a limited extent, the liquid and / or solid isocyanate-reactive component can also contain a non-aromatic C _4-18 polycarboxylic acid.

The molar ratio of aromatic carboxyl groups to the sum of aromatic and aliphatic carboxyl groups in the liquid isocyanate-reactive component and, if used, the solid isocyanate-reactive component is preferably at least 10 mol%, in particular at least 15 mol%. Aromatic carboxyl groups are those carboxyl groups which are bonded directly to an aromatic ring. Aliphatic carboxyl groups are those carboxyl groups which are bonded to a non-aromatic carbon atom. The reactive diluents (aliphatic branched C _24-66 polycarboxylic acids, alicyclic C _24-66 polycarboxylic acids, aliphatic branched C _24-66 monocarboxylic acids, alicyclic _acids ) contribute to the aliphatic carboxyl groups
C _{24-66 monocarboxylic} acids and _partial esters of non-aromatic polycarboxylic acids) and optionally also used non-aromatic C _4-18 polycarboxylic acids. The contribution of the reactive diluents to the aliphatic carboxyl groups can expediently be calculated as W / E, where W is the amount of reactive diluent (in g) and E is the equivalent weight (in g / mol). The equivalent weight E in turn can be calculated from the acid number AV (in mgKOH / g) as E = 56.11 / AV, where 56.11 is the molecular weight of KOH. The acid number AV is usually specified by the manufacturers of dimer fatty acids or trimer fatty acids.

In suitable embodiments, the weight ratio of aromatic C _8-18 polycarboxylic acid and / or anhydride thereof to the chain-extending and / or crosslinking reactive diluent and / or chain-closing reactive diluent is 1:20 to 20: 1, preferably 1:10 to 10: 1.

Suitable aromatic polycarboxylic acids are aromatic C _8-18 polycarboxylic acids, such as phthalic acid, terephthalic acid, isophthalic acid, aminoisophthalic acid, trimellitic acid, tetracarboxybenzene, naphthalenedicarboxylic acid, bisphenyldicarboxylic acid etc. and their anhydrides.

Suitable non-aromatic polycarboxylic acids are aliphatic polycarboxylic acids, such as succinic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, cyclohexyldicarboxylic acids, tetrahydrophthalic acids, citric acid, tartaric acid and anhydrides thereof.

Optionally, the liquid isocyanate-reactive component and / or the solid isocyanate-reactive component comprises a neutralizing agent for neutralizing the polycarboxylic acid. Preferred neutralizing agents are amines, especially tertiary amines. Examples of suitable amines are triethylamine, tri (n-propyl) amine, N-methyl-N, N-di (n-butyl) amine, N-methyl-piperidine, N-methyl-morpholine, permethylated diethylene triamine, triethylene diamine (1 , 4-diazabicyclo [2.2.2] octane, DABCO), triethanolamine, N, N-dimethylbenzylamine.

The liquid isocyanate-reactive component optionally comprises compounds which have at least two isocyanate-reactive groups, for example -OH, -SH, -NH ₂ or -NHR ² , in which R ² therein is, independently of one another, hydrogen, methyl, ethyl, iso-propyl, n Propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl may have.

These are preferably diols or polyols, such as hydrocarbon diols having 2 to 20 carbon atoms, e.g. Ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,1-dimethylethane-1,2-diol, 1,6-hexanediol, 1,10-decanediol, bis (4-hydroxycyclohexane) isopropylidene, tetramethylcyclobutanediol, 1, 2-, 1,3- or 1,4-cyclohexanediol, cyclooctanediol, norbornanediol, pinanediol, decalinediol, etc., their esters with short-chain dicarboxylic acids, such as adipic acid, cyclohexanedicarboxylic acid, or aliphatic diamines, such as methylene and isopropylidene bis ( cyclohexylamine), piperazine, 1,2-, 1,3- or 1,4-diaminocyclohexane, 1,2-, 1,3- or 1,4-cyclohexane-bis- (methylamine), etc., dithiols or polyfunctional alcohols , secondary or primary amino alcohols, such as ethanolamine, diethanolamine, monopropanolamine, dipropanolamine etc. or thioalcohols, such as thioethylene glycol.

Diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, pentaerythritol, 1,2- and 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, 2-ethyl-1,4- butanediol, 1,2-, 1,3- and 1,4-dimethylolcyclohexane, 2,2-bis (4-hydroxycyclohexyl) propane, glycerol, trimethylolethane, trimethylolpropane, trimethylolbutane, dipentaerythritol, erythritol and Sorbitol, 2-aminoethanol, 3-amino-1-propanol, 1-amino-2-propanol or 2- (2-aminoethoxy) ethanol, bisphenol A, or butanetriol.

Furthermore, polyether or polyesterols or polyacrylate polyols with an average OH functionality of 2 to 10 are also suitable, and polyamines, such as, for. B. polyethyleneimine or free amine-containing polymers of z. B. Poly-N-vinylformamide.

The liquid isocyanate-reactive component optionally comprises small amounts of water. The amount of water added is preferably at most 0.01 to 0.2 equivalents, based on the NCO content of the isocyanate component. The addition of water serves to introduce an additional blowing reaction and / or to modify the material properties with a proportion of polyurea.

In general, the components are mixed in the presence of a polyaddition catalyst. The polyaddition catalyst allows decarboxylation and polyamide formation to take place under mild conditions. The liquid isocyanate component, the liquid isocyanate-reactive component and / or, if used, the solid isocyanate-reactive component preferably contains a polyaddition catalyst.

Catalysts commonly used in polyurethane chemistry can be used as polyaddition catalysts. These are compounds that accelerate the reaction of the reactive hydrogen atoms, especially the polycarboxylic acids, with the organic polyisocyanates. Both Lewis bases and Lewis acids are effective catalysts. The most important Lewis bases are tertiary amines with different structures. The most important catalytically active Lewis acids are organic metal compounds.

The proportion of the polyaddition catalyst, based on the total weight of the components, is preferably 0.01 to 2% by weight, particularly preferably 0.02 to 1% by weight and in particular 0.05 to 0.5% by weight. In a preferred embodiment of the present invention, no further catalysts are used in addition to a Lewis base.

Suitable polyaddition catalysts are organic metal compounds, preferably organic titanium compounds, such as tetra (2-ethylhexyl) titanate, or organic tin compounds, such as tin (II) salts of organic carboxylic acids, for example tin (II) acetate, tin (II) - octoate, tin (II) ethyl hexanoate, tin (II) laurate and the dialkyltin (IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, dioctyltin diacetate, but also other metal-based catalysts such as carboxylates of alkaline earth metals, e.g. B. Magnesium stearate, but also aluminum salts, borates, etc. as described in an overview in C. Gürtler, K. Danielmeier, Tetrahedron Letters 45 (2004) 2515-2521 .

Tertiary amines such as triethylamine, tributylamine, N, N-dimethylcyclohexylamine, N, N-dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N, N, N ', N'-tetramethylethylenediamine, N, N are also suitable , N ', N'-tetramethylbutylene diamine, N, N, N', N'-tetramethyl-1,6-hexylene diamine, pentamethyl-diethylene triamine, tetramethyl-diaminoethyl ether, bis (dimethylaminopropyl) urea, dimethylpiperazine, N-methylimidazole, 1 , 2-dimethylimidazole, 1-aza-bicyclo- [3.3.0] octane, 1,4-diaza-bicyclo- [2.2.2] octane (DABCO), and alkanolamine compounds such as triethanolamine, tris-isopropanolamine, N-methyldiethanolamine and N-ethyl-diethanolamine and dimethylethanolamine.

Other possible catalysts are: tris- (dialkylamino) -s-hexahydrotriazine, in particular tris- (N, N-dimethylamino) -s-hexahydrotriazine. Tetraalkylammonium salts such as, for example, N, N, N-trimethyl-N- (2-hydroxypropyl) formate, N, N, N-trimethyl-N- (2-hydroxypropyl) -2-ethyl-hexanoate are also suitable , Tetraalkyl-ammonium hydroxides such as tetramethylammonium hydroxide, alkali hydroxides such as sodium hydroxide, alkali metal alcoholates such as sodium methylate and potassium isopropylate, and alkali metal or alkaline earth metal salts of fatty acids with 1 to 20 carbon atoms and optionally pendant OH groups.

It is also possible to use catalysts which are reactive toward isocyanates. In addition to at least one tertiary amino group, they contain a primary or secondary amino group or a hydroxyl group. These include, for example, N, N-dimethylaminopropylamine, bis- (dimethylaminopropyl) amine, N, N-dimethylaminopropyl-N'-methylethanolamine, dimethylaminoethoxyethanol, bis- (dimethylaminopropyl) amino-2-propanol, N, N-dimethylaminopropyl-dipropanolamine , N, N, N'-trimethyl-N'-hydroxyethyl-bisaminoethyl ether, N, N-dimethylaminopropylurea, N- (2-hydroxypropyl) imidazole, N- (2-hydroxyethyl) imidazole, N- (2- Aminopropyl) imidazole and / or the in EP-A 0 629 607 described reaction products of ethyl acetoacetate, polyether polyols and 1- (dimethylamino) -3-aminopropane.

Bis (alkylamino) alkyl ethers, such as bis (2-dimethylaminoethyl) ether or 2,2'-dimorpholinodiethyl ether, and 2- (2-dialkylaminoalkoxy) alkanols, 2- (2-dimethylaminoethoxy) ethanol, are preferred because they are used in addition to catalysts Polyaddition reaction are also strong blowing or blowing catalysts (blow catalysts). Also preferred are 1,8-diazabicyclo [5.4.0] undec-7-ene and DABCO.

The liquid isocyanate component and / or the liquid isocyanate-reactive component, in particular the liquid isocyanate-reactive component, preferably contains a foam stabilizer. Foam stabilizers are usually used in amounts of 0.01 to 5% by weight, based on the total weight of the components. Surface-active substances are suitable as foam stabilizers. Modified polysiloxanes, such as trisiloxane surfactants, polyether siloxane or polysiloxane-polyoxyalkylene block polymers, have proven particularly useful. Such compounds are available from Evonik under the name Tegostab®. Copolymers based on ethylene oxide and butylene oxide, copolymers which are prepared from N-vinylpyrrolidone and maleic acid esters or oligomeric polyacrylates with polyoxyalkylene and fluoroalkane radicals as side groups can be mentioned as non-silicone-based stabilizers.

Optionally, the liquid isocyanate component and / or the liquid isocyanate-reactive component, in particular the liquid isocyanate-reactive component, contains a solvent in order to achieve sufficient solubility of additives, such as polyaddition catalyst, polycarboxylic acid, etc. Low flash point solvents are preferred. Triethyl phosphate, dibutyl glycol acetate, biodiesel (Sovermol 1058), high-boiling petroleum fractions (e.g. Total EDC aliphatic base oil, Shellsol aromatic hydrocarbons), ionic liquids (Basionics) or classic plasticizers such as phthalates (e.g. Palatinol N ).

1. (a) Phosphorestersalze von aminogruppenhaltigen Oligomeren oder Polymeren, wie beispielsweise Phosphorestersalze von gegebenenfalls fettsäuremodifizierten oder alkoxylierten (insbesondere ethoxylierten) Polyaminen, Phosphorestersalze von Epoxid-Polyamin-Addukten, Phosphorestersalze von aminogruppenhaltigen Acrylat- oder Methacrylatcopolymeren und Phosphorestersalze von Acrylat-Polyamin-Addukten,
2. (b) Mono- oder Diester der Phosphorsäure, wie beispielsweise Mono- oder Diester der Phosphorsäure mit Alkyl-, Aryl-, Aralkyl- oder Alkylaryl-Alkoxylaten (z. B. Phosphorsäure-mono- oder -di-ester von Nonylphenolethoxylaten, Isotridecylalkoholethoxylaten, butanolgestarteten Alkylenoxidpolyethern), Mono- oder Diester der Phosphorsäure mit Polyestern (z. B. Lactonpolyestern, wie Caprolactonpolyestern oder gemischten Caprolacton/Valerolacton-Polyestern),
3. (c) saure Dicarbonsäurehalbester, beispielsweise saure Dicarbonsäurehalbester (insbesondere der Bernsteinsäure, Maleinsäure oder Phthalsäure) mit Alkyl-, Aryl-, Aralkyl- oder Alkylaryl-Alkoxylaten (z. B. Nonylphenolethoxylaten, Isotridecylalkoholethoxylaten oder Butanol-gestarteten Alkylenoxid polyethern),
4. (d) Polyurethan-Polyamin-Addukte,
5. (e) polyalkoxylierte Mono- oder Diamine (z. B. ethyoxyliertes Oleylamin oder alkoxyliertes Ethylendiamin),
6. (f) Reaktionsprodukte von ungesättigten Fettsäuren mit Mono-, Di- und Polyaminen, Aminoalkoholen und ungesättigten 1,2-Dicarbonsäuren und deren Anhydriden und deren Salze und Umsetzungsprodukte mit Alkoholen und/oder Aminen.

Optionally, the liquid isocyanate component and / or the liquid isocyanate-reactive component, in particular the liquid isocyanate-reactive component, contains a dispersant in order to achieve sufficient dispersion of additives, such as polyaddition catalyst, polycarboxylic acid, etc. The following groups of dispersants have a particularly good effect in the compositions according to the invention:

1. (a) phosphorus ester salts of amino group-containing oligomers or polymers, such as, for example, phosphorus ester salts of optionally fatty acid-modified or alkoxylated (in particular ethoxylated) polyamines, phosphorus ester salts of epoxy-polyamine adducts, phosphorus ester salts of amino group-containing acrylate or methacrylate copolymers, and phosphorus ester amine salts of acrylate copolymers,
2. (b) mono- or diesters of phosphoric acid, such as, for example, mono- or diesters of phosphoric acid with alkyl, aryl, aralkyl or alkylaryl alkoxylates (for example phosphoric acid mono- or di-esters of nonylphenol ethoxylates, isotridecyl alcohol ethoxylates, butanol-started alkylene oxide polyethers), mono- or diesters of phosphoric acid with polyesters (e.g. lactone polyesters, such as caprolactone polyesters or mixed caprolactone / valerolactone polyesters),
3. (c) acidic dicarboxylic acid semi-esters, for example acidic dicarboxylic acid half-esters (especially succinic acid, maleic acid or phthalic acid) with alkyl, aryl, aralkyl or alkylaryl alkoxylates (e.g. nonylphenol ethoxylates, isotridecyl alcohol ethoxylates or butanol-started) alkylene oxide polyether
4. (d) polyurethane-polyamine adducts,
5. (e) polyalkoxylated mono- or diamines (e.g. ethoxylated oleylamine or alkoxylated ethylenediamine),
6. (f) Reaction products of unsaturated fatty acids with mono-, di- and polyamines, amino alcohols and unsaturated 1,2-dicarboxylic acids and their anhydrides and their salts and reaction products with alcohols and / or amines.

Suitable dispersants are commercial products under the trade name Disperbyk, e.g. B. Disperbyk 190 available.

Optionally, the liquid isocyanate component and / or the liquid isocyanate-reactive component, in particular the liquid isocyanate-reactive component, contain a rheology modifier, in particular a polymeric rheology modifier, in order to set a suitable initial viscosity and / or rheological behavior. Suitable polyacrylic acids or their salts are available under the name Sokalan® from BASF SE. Suitable cationic polymers are available under the trade name Luviquat.

Optionally, the liquid isocyanate-reactive component and / or the solid isocyanate-reactive component can contain a silicate source. Silicic acid, water glass or water glass in powder form are suitable for this. B. with an SiO ₂ / alkali oxide mass ratio in the range of about 2: 0.8 to 2: 1.2.

In certain embodiments, the liquid isocyanate component, the liquid isocyanate-reactive component and / or the solid isocyanate-reactive component contains a flame retardant. Suitable flame retardants are, for example, tricresyl phosphate, tris (2-chloroethyl) phosphate, tris (2-chloropropyl) phosphate, tris (1,3-dichloropropyl) phosphate, tris (2,3-dibromopropyl) phosphate and tetrakis (2-chloroethyl) ethylene diphosphate, triphenyl phosphate, triethyl phosphate, tetrabromobisphenol A, decabromodipentyl ether. In addition to the halogen-substituted phosphates already mentioned, inorganic flame retardants such as red phosphorus, aluminum oxide hydrate, antimony oxide, antimony trioxide, arsenic oxide, zinc borate, ammonium polyphosphate, expanded graphite and calcium sulfate or cyanuric acid derivatives, such as, for. B. melamine or fillers, such as limestone powder, can be used. In addition, both non-expanded and already expanded layer materials, such as raw vermiculite or expanded vermiculite, can be used as flame retardants. Mixtures of at least two flame retardants, such as. B. ammonium polyphosphates and melamine and / or expanded graphite can be used.

The flame retardants preferably contain expandable graphite and oligomeric organophosphorus flame retardants. Expandable graphite is generally known.

Inorganic flame retardants such as ammonium phosphate, red phosphorus, expandable graphite, clay minerals (vermiculite, bentonite, talc), aluminum hydroxide, magnesium hydroxide or calcium hydroxide are particularly preferred.

The invention also relates to a method for filling cavities in mining, tunneling, civil engineering or in oil and gas production with a non-fire-propagating polyamide foam, wherein the above-defined liquid isocyanate component, liquid isocyanate-reactive component and, if appropriate, solid isocyanate-reactive component are mixed and introduces the mixture into the cavity. If used, the solid isocyanate-reactive component can advantageously be dispersed in the liquid isocyanate-reactive component before it is mixed with the liquid isocyanate component. The mixing is suitably carried out in a mixing head, to which the components are pumped separately and in which they are mixed by using a mixing element which is located in the mixing head. If existing natural rock formations are not sufficient to limit leakage and / or leakage, formwork can be provided. Since the reaction takes place practically immediately, the mixture emerging from an applicator quickly foams and solidifies very quickly, so that the construction of dense formwork, which is generally expensive, can be avoided, as well as the loss of material due to leakage in the event of filling large cavities. Finally, the method according to the invention can be applied with the help of simple formwork, ie with formwork that is not absolutely tight and with the help of coarse, loosely assembled boards, possibly covered with a textile or a film, since the leakage of the expanding foam is limited to a very small proportion by the non-abutting parts due to the very rapid expansion.

The polyamide foams obtainable according to the invention can also be used as fire protection foam in building construction (e.g. for wall breakthroughs, fire bolts). Since these foams are also characterized by their low flammability and flammability, high-temperature stability and non-fire-propagating properties compared to standard foams such as polystyrene or polyurethane, the improved embrittlement and deformation of the material can be used for the thermal insulation of industrial pipes and / or systems or heated ones Pipelines and / or (oil) pipelines or heating components can be advantageous. Another possible area of application is acoustic damping, which can be applied or prefabricated on construction sites. Less foamed versions of this material can also be used as an injection medium for cementing cracks in mining or civil engineering or in the oil field when drilling or repairing boreholes.

• Figur 1 zeigt den Temperatur-Zeit-Verlauf des Punking-Tests nach BS 5946:1980 für den Schaum gemäß Beispiel 9.
• Figur 2 zeigt schematisch die Positionierung des Bunsenbrenners und der Temperatursonden beim Punking-Test.

The invention is illustrated in more detail by the following examples and figures.

• Figure 1 shows the temperature-time curve of the punking test according to BS 5946: 1980 for the foam according to Example 9.
• Figure 2 shows schematically the positioning of the Bunsen burner and the temperature probes in the punking test.

The following commercially available chemicals were used for the examples below: Lupranat M10R (BASF) Polymer methylene diphenyl isocyanate (NCO content 31.7%, nominal NCO functionality 2.2) Lupranat M20R (BASF) Polymer methylene diphenyl isocyanate (NCO content 31.4%, nominal NCO functionality 2.7) Lupranat M200R (BASF) Polymer methylene diphenyl isocyanate (NCO content 31%, nominal NCO functionality 3) Jeffcat ZR 50 (Huntsman) N, N-bis (3-dimethylaminopropyl) -N-isopropanolamine Jeffcat ZR 70 (Huntsman) 2- (2-dimethylaminoethoxy) ethanol Lupragen N106 (BASF) 4,4- (oxydi-2,1-ethanediyl) bismorpholine Lupragen N201 (BASF) Diazabicyclooctane Lupragen N600 (BASF) 1,3,5-tris (dimethylaminopropyl) sym hexahydrotriazine Lupragen TCPP (BASF) Trichloropropyl phosphate Empol 1062 (BASF) Tall oil-based fatty acid dimer (distilled, partially hydrogenated) Empol 1043 (BASF) Tall oil-based fatty acid trimer Pripol 1017 (Croda) Fatty acid dimer (acid number 190-197 mgKOH / g) Pripol 1040 (Croda) Fatty acid trimer (acid number 184-194 mgKOH / g) Tegostab B 8407 (Evonik) Polyoxyalkylene polysiloxane

The liquid components 1 and 2 described below and optionally the solid component 2.1 are mixed with a mechanical stirrer or wooden spatula at ambient temperature. The mixtures foam spontaneously and form a solid polyamide foam after curing.

Example 1:

• Component 1: 6 g Lupranat M20R.
• Component 2: 5 g Empol 1062 and 0.5 g Jeffcat ZR 70.
• Component 2.1: 1.2 g isophthalic acid.

Example 2:

• Component 1: 6 g Lupranat M20R.
• Component 2: 5 g Empol 1062 and 0.5 g Jeffcat ZR 70 and 1.2 g isophthalic acid (pre-dissolved in 4 g triethyl phosphate).

Example 3:

• Component 1: 6 g Lupranat M20R.
• Component 2: 5 g Empol 1062 and 0.5 g Jeffcat ZR 70 and 0.2 g Tegostab B 8407 and 1.2 g isophthalic acid (dispersed therein).

Example 4:

• Component 1: 6 g Lupranat M20R.
• Component 2: 4.5 g Empol 1043 and 0.5 g Jeffcat ZR 70.
• Component 2.1: 1.2 g terephthalic acid.

Example 5:

• Component 1: 6 g Lupranat M10R.
• Component 2: 4.5 g Empol 1043 and 0.5 g Jeffcat ZR 70 and 0.2 g Tegostab B 8407.
• Component 2.1: 1.2 g isophthalic acid

Example 6:

According to Example 5, a foam piece with a density of 70 kg / m ^{3 was} produced. A prism resulting from this piece of foam was subjected to a mechanical pressure test. The average compressive strength was 0.2 N / mm ² with a compression of 10%.

Example 7:

According to Example 5, a foam piece with a density of 75 kg / m ^{3 was} produced. A plate with the dimensions 20x20x4 cm resulting from this foam piece was examined for its thermal conductivity. This had a thermal conductivity of 51 mW / (m * K).

Example 8:

A piece of foam produced according to Example 5 was examined thermogravimetrically. The decomposition of the foam started at a temperature of 420 ° C.

Example 9:

According to Example 5, a batch with four times the amount of catalyst (relative to the total amount of the other components) and an increased batch size for producing 200 g of curable mixture was carried out to investigate the heat of reaction. The components preheated to 30 ° C. were mixed and the reaction temperature was measured during the foaming process. The maximum reaction temperature was 50 ° C.

A 12x12x12 cm cube with a density of 45 kg / m ³ obtained from the resulting foam block was subjected to a punking test according to BS 5946: 1980 in order to investigate the propagation of fire. Two temperature probes were inserted into the foam piece and the foam was then flamed for 50 min with the Bunsen burner flame lit (see Figure 2 ). After the flame had been applied, the temperature was measured on the temperature probe T2 until it had dropped to <40 ° C; the temperature curve is in Figure 1 shown. In the experiment, the recorded temperatures dropped immediately after the flaming had ended. The fire did not continue, nor did it spread. The cut foam cube was undamaged in the upper third after the test. In the damaged area of the test specimen, the foam remained in the form of a charred substance with a residual strength. Since the fire did not persist and the material did not completely coke during the test, the foam body passed the test.

Example 10 (comparative example):

Component 1: 6 g Lupranat M10R.

Component 2: 4 g Pripol 1017, 2 g Pripol 1040 and 0.6 g water and 1 g 4,4- (oxydi-2,1-ethanediyl) bismorpholine (Lupragen N106) and 0.5 g Tegostab B 8407. 14 s after mixing the first component with the second component, the mixture begins to foam. The foaming process ends after 2 minutes with a 14-fold increase in volume. The result is a non-tacky, firm foam which, in contrast to the foams from Examples 1-5, has a very fine foam structure.

Example 11:

• Component 1: 6 g Lupranat M10R.
• Component 2: 4 g Pripol 1017, 2 g Pripol 1040 and 0.6 g water and 1 g 4,4- (oxydi-2,1-ethanediyl) bismorpholine (Lupragen N106) and 0.5 g Tegostab B 8407. Component 2.1 : 1.2 g isophthalic acid.

In contrast to the foams from Examples 1-5, this foam has a very fine foam structure.

Example 12:

• Component 1: 6 g Lupranat M20R.
• Component 2: 2 g Pripol 1017, 4 g Pripol 1040, 0.6 g water, 0.15 g 4,4- (oxydi-2,1-ethanediyl) bismorpholine (Lupragen N106), 1.0 g Jeffcat ZR50, 0 , 5 g Tegostab B 8407 and 3 g isophthalic acid (homogeneously dispersed therein).

The resulting foam has a finer foam structure than Examples 1-5. A piece of foam produced according to this recipe was subjected to a punking test according to BS 5946: 1980 analogously to Example 9. The foam body passed the test. Compared to the foams from Examples 10 and 11, this foam has better fire behavior, i. H. it is less flammable, self-extinguishing, carbonized and melts less.

Example 13:

• Component 1: 6 g Lupranat M20R.
• Component 2: 2 g Pripol 1017, 4 g Pripol 1040, 0.6 g water, 0.15 g 4,4- (oxydi-2,1-ethanediyl) bismorpholine (Lupragen N106), 1.0 g Jeffcat ZR50, 0 , 5 g Tegostab B 8407, 2 g isophthalic acid and 1 g trimellitic acid (homogeneously dispersed therein).

The resulting foam has a finer foam structure than Examples 1-5, but a better fire behavior than Examples 10 and 11 (less flammable, self-extinguishing, carbonized and melts less).

Example 14:

Polyamide foams were produced from the components and amounts used (in g) summarized in the following table as follows: All components with the exception of the Lupranat M200R were mixed; then the Lupranat M200R was added. The mixtures foamed and formed a solid polyamide foam after curing. After 12 hours, a 12x12x12 cm ³ cube was cut out of the foam pieces. The fire behavior of the cubes was investigated in the punking test described in Example 9. The temperatures T1 (bottom) and T2 (middle) reached after 10 and 20 minutes are also given in the table. A B C-1 C-2 C-3 Lupranat M200R 72.0 72.0 63.5 55.8 51.3 Isophthalic acid 40.0 31.3 24.4 17.6 Adipic acid 35.0 Pripol 1040 102.0 102.0 120.0 133.4 146.3 water 0.6 0.6 0.6 0.6 0.6 Lupragen N201 8.0 8.0 8.0 8.0 8.0 Lupragen N600 4.0 4.0 4.0 4.0 4.0 Lupragen TCPP 25.0 25.0 25.0 25.0 25.0 Triethyl phosphate 15.0 15.0 15.0 15.0 15.0 T1 (after 10/20 * min) 364 * 359 * 140 158 239 T2 (after 10/20 * min) 75 * 172 * 46 120 90

The comparison of experiments A and B shows that after 20 min at comparable temperature T1, the temperature T2 in experiment A is only moderately increased, while T2 in experiment B is increased significantly more. This proves that foam A shows less fire-propagating behavior.

The series C-1, C-2 and C-3 shows that the flammability of the foam increases with a decreasing ratio of isophthalic acid / Pripol 1040, as can be seen from the greater increase in temperature T1 after 10 minutes.

Claims (14)

1. Process for producing polyamide foams which do not propagate fire by mixing

   (i)a liquid isocyanate component which contains at least one polyisocyanate and in which the molar ratio of aromatic isocyanate groups to the sum of aromatic and aliphatic isocyanate groups is at least 60 mol% with

   (ii) at least one liquid isocyanate-reactive component which contains a reactive diluent, where the reactive diluent comprises

   (a) a chain-extending and/or crosslinking reactive diluent selected from among aliphatic branched C_24-66-polycarboxylic acids, alicyclic C_24-66-polycarboxylic acids and partial esters of polycarboxylic acids having at least two unesterified carboxyl groups and/or

   (b) a chain-terminating reactive diluent selected from among aliphatic branched C_24-66-monocarboxylic acids, alicyclic C_24-66-monocarboxylic acids and partial esters of polycarboxylic acids having one unesterified carboxyl group, and

   (iii) optionally a solid isocyanate-reactive component,

   wherein the liquid isocyanate-reactive component and/or the solid isocyanate-reactive component comprises an aromatic C_8-18-polycarboxylic acid and/or an anhydride thereof.
2. Process according to Claim 1, characterized in that the liquid isocyanate component contains diphenylmethane diisocyanate, a mixture of monomeric diphenylmethane diisocyanate and homologues of diphenylmethane diisocyanate having more than two rings or prepolymers of diphenylmethane diisocyanate or mixtures thereof.
3. Process according to Claim 1 or 2, characterized in that the aliphatic, branched C_24-66-polycarboxylic acid and/or alicyclic C_24-66-polycarboxylic acid is selected from among dimeric fatty acids, trimeric fatty acids and mixtures thereof, which are optionally hydrogenated.
4. Process according to any of the preceding claims, characterized in that the molar ratio of aromatic carboxyl groups to the sum of aromatic and aliphatic carboxyl groups in (ii) and (iii) is at least 10 mol%.
5. Process according to any of the preceding claims, characterized in that the liquid isocyanate component, the liquid isocyanate-reactive component and/or the solid isocyanate-reactive component contains a polyaddition catalyst.
6. Process according to Claim 5, characterized in that the polyaddition catalyst is selected from among tin-organic compounds, tertiary amines and alkaline earth metal salts.
7. Process according to any of the preceding claims, characterized in that the liquid isocyanate component and/or the liquid isocyanate-reactive component contains a foam stabilizer.
8. Process according to any of the preceding claims, characterized in that the liquid isocyanate component, the liquid isocyanate-reactive component and/or the solid isocyanate-reactive component contains a flame retardant.
9. Process for filling cavities in mining, tunnel construction, civil engineering or in oil and gas recovery using a polyamide foam which does not propagate fire, wherein the liquid isocyanate component, the liquid isocyanate-reactive component and optionally the solid isocyanate-reactive component as defined in Claim 1 are mixed and the mixture is introduced into the cavity.
10. Process according to Claim 9, characterized in that the cavity is delimited by means of formwork and the mixture is introduced into the delimited cavity.
11. Polyamide foam obtainable by the process according to any of Claims 1 to 8.
12. Use of the polyamide foam according to Claim 11 as fire protection foam.
13. Use of the polyamide foam according to Claim 11 as thermal insulation.
14. Use of the polyamide foam according to Claim 11 as acoustic damping.

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